The Distribution of Atomic Carbon in the Orion Giant Molecular Cloud 1

Ikeda, Masafumi; Oka, Tomoharu; Tatematsu, Ken’ichi; Sekímoto, Yutaro; Yamamoto, Satoshi

doi:10.1086/338761

Cited by 118 publications

(137 citation statements)

References 46 publications

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“…This is most likely a consequence of the small size of our C i map. Because C i emission follows CO in all studied cases (e.g., Ikeda et al 2002;Zhang et al 2007), a different distribution is highly unlikely.…”

Section: Co and C I 1 → 0 Spectramentioning

confidence: 96%

“…Strong evidence shows that C i and CO luminosities have a tight correlation in galaxies, independent of physical environment, IR luminosity, or redshift (e.g., Papadopoulos & Greve 2004;Zhang et al 2007;Walter et al 2011). This suggests that C i emission arises from the same volume and shares similar excitation temperature as CO (e.g., Ikeda et al 2002). Constant ratios between the column densities of C i, 12 CO, and H 2 are expected over a large range of physical conditions (e.g., Papadopoulos & Greve 2004;Walter et al 2011).…”

Section: Molecular Gas Mass Estimates Using C Imentioning

confidence: 99%

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Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Zhang

Henkel

Gao

et al. 2014

A&A

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We report mapping observations of the 12 CO J = 3 → 2, 4 → 3, 6 → 5, and 7 → 6 transitions and the C i 3 P 1 → 3 P 0 (C i) 492 GHz transition toward the central 40 ×40 region of the Circinus galaxy, using the Atacama Pathfinder EXperiment (APEX) telescope. We also detected 13 CO J = 3 → 2 at the central position of Circinus. These observations are to date the highest CO transitions reported in Circinus. With large velocity gradient (LVG) modeling and likelihood analysis we try to obtain density, temperature, and column density of the molecular gas in three regions: the nuclear region (D < 18 ∼ 360 pc), the entire central 45 (D < 45 ∼ 900 pc) region, and the star-forming (S-F) ring (18 < D < 45 ). In the nuclear region, we can fit the CO excitation with a single excitation component, yielding an average condition of n H 2 ∼ 10 3.2 cm −3 , T kin ∼ 200 K, and d /dr ∼ 3 km s −1 pc −1 . In the entire 45 region, which covers both the nucleus and the S-F ring, two excitation components are needed with n H 2 ∼ 10 4.2 cm −3 and 10 3.0 cm −3 , T kin ∼ 60 K and 30 K, and M H 2 ∼ 2.3 × 10 7 M and 6.6 × 10 7 M , respectively. The gas excitation in the S-F ring can also be fitted with two LVG components, after subtracting the CO fluxes in the 18 nuclear region. The S-F ring region contributes 80% of the molecular mass in the 45 region. For the entire 45 region, we find a standard conversion factor of N(H 2 )/I CO 1→0 = 0.37 × 10 20 cm −2 (K km s −1 ) −1 , about 1/5 of the Galactic disk value. The luminosity ratios of C i and 12 CO J = 3 → 2 (R CI/CO 3→2 ) in Circinus basically follow a linear trend, similar to that obtained in high-redshift galaxies. The average R CI/CO J = 3 → 2 in Circinus is found to be ∼0.2, lying at an intermediate value between non-AGN nuclear regions and high-redshift galaxies.

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Section: Co and C I 1 → 0 Spectramentioning

confidence: 96%

Section: Molecular Gas Mass Estimates Using C Imentioning

confidence: 99%

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Zhang

Henkel

Gao

et al. 2014

A&A

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“…Furthermore, such low temperatures would require extreme CO column densities to raise photon trapping to such levels that the emission from the higher J transitions could be reproduced. (2) T kin > 50 K is also not likely because of the temperature deduced from [Ci] and the close association of CO and Ci, which appears to be independent of the environment (e.g., Ikeda et al 2002;Zhang et al 2007 local galactic disk (Weiß et al 2005), the [ 12 CO]/[H 2 ] abundance ratio should be of order 10 −4 (e.g., Frerking et al 1982). The resulting velocity gradient of dv/dr = 10 3 km s −1 pc −1 would be far too large in view of the measured line width (e.g., Weiß et al 2003) and the kinetic temperature such extreme conditions would induce (e.g., Wiklind & Henkel 2001).…”

Section: Large Velocity Gradient Model Calculationsmentioning

confidence: 99%

Weak¹³CO in the Cloverleaf quasar: evidence for a young, early generation starburst

Henkel¹,

Downes

Weiß³

et al. 2010

A&A

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Observations of 12 CO at high redshift indicate rapid metal enrichment in the nuclear regions of at least some galaxies in the early universe. However, the enrichment may be limited to nuclei that are synthesized by short-lived massive stars, excluding classical "secondary" nuclei like 13 C. Testing this idea, we used the IRAM Interferometer to tentatively detect the 13 CO J = 3 → 2 line at a level of 0.3 Jy km s −1 toward the Cloverleaf quasar at z = 2.5. This is the first observational evidence for 13 C at high redshift. The 12 CO/ 13 CO J = 3 → 2 luminosity ratio is with 40 +25 −8 much higher than ratios observed in molecular clouds of the Milky Way and in the ultraluminous galaxy Arp 220, but may be similar to that observed toward NGC 6240. Large Velocity Gradient models simulating seven 12 CO transitions and the 13 CO line yield 12 CO/ 13 CO abundance ratios in excess of 100. It is possible that the measured ratio is affected by a strong submillimeter radiation field, which reduces the contrast between the 13 CO line and the background. It is more likely, however, that the ratio is caused by a real deficiency of 13 CO. This is already apparent in local ultraluminous galaxies and may be even more severe in the Cloverleaf because of its young age ( < ∼ 2.5 Gyr). A potential conflict with optical data, indicating high abundances also for secondary nuclei in quasars of high redshift, may be settled if the bulk of the CO emission is originating sufficiently far from the active galactic nucleus of the Cloverleaf.

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“…The line profiles from these observations were usually fitted with single Gaussians in spite of apparent asymmetries seen in some cases (e.g., Fig. 7 in Ikeda et al 2002). Besides, the measured radial velocities were not corrected for different beamsizes.…”

Section: [C I] and Co Lines As Probes Of α 2 /μmentioning

confidence: 99%

“…The observations of the [C i] (1-0) line towards 9 deg 2 area of the Orion A cloud and 6 deg 2 area of the Orion B cloud with a grid spacing of 3 were carried out with the 1.2 m Mount Fuji submillimeter telescope (Ikeda et al 2002). These observations were complemented with the 13 CO (1-0) dataset presented in Table 3 in Ikeda et al At the frequency 492 GHz, the spatial and velocity resolutions were, respectively, 2.2 and 1.0 km s −1 , whereas at frequency 110 GHz they were 1.6 and 0.3 km s −1 .…”

Section: Sourcementioning

confidence: 99%

Searching for spatial variations ofα²/μin the Milky Way

Levshakov

Molaro²,

Reimers

2010

A&A

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Aims. We probe the dependence of α 2 /μ on the ambient matter density by means of spectral observations in submm-and mm-wave bands. Methods. A procedure is suggested for exploring the value of F = α 2 /μ, where μ = m e /m p is the electron-to-proton mass ratio, and α = e 2 /( c) is the fine-structure constant. The fundamental physical constants, which are measured in different physical environments of high (terrestrial) and low (interstellar) densities of baryonic matter are supposed to vary in chameleon-like scalar field models, which predict that both masses and coupling constant may depend on the local matter density. The parameter ΔF/F = (F obs − F lab )/F lab can be estimated from the radial velocity offset, ΔV = V rot − V fs , between the low-laying rotational transitions in carbon monoxide 13 CO and the fine-structure transitions in atomic carbon [C i]. A model-dependent constraint on Δα/α can be obtained from ΔF/F using Δμ/μ independently measured from the ammonia method. Results. Currently available radio astronomical datasets provide an upper limit on |ΔV| < 110 m s −1 (1σ). When interpreted in terms of the spatial variation of F, this gives |ΔF/F| < 3.7 × 10 −7 . An order of magnitude improvement in this limit will allow us to independently test a non-zero value of Δμ/μ = (2.2 ± 0.4 stat ± 0.3 sys ) × 10 −8 , recently found with the ammonia method. Considering that the ammonia method restricts the spatial variation of μ at the level of |Δμ/μ| ≤ 3 × 10 −8 and assuming that ΔF/F is the same in the entire interstellar medium, one obtains that the spatial variation of α does not exceed the value |Δα/α| < 2 × 10 −7 . Since extragalactic gas clouds have similar densities to those in the interstellar medium, the bound on Δα/α is also expected to be less than 2 × 10 −7 at high redshift if no significant temporal dependence of α is present.

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The Distribution of Atomic Carbon in the Orion Giant Molecular Cloud 1

Cited by 118 publications

References 46 publications

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Weak¹³CO in the Cloverleaf quasar: evidence for a young, early generation starburst

Searching for spatial variations ofα²/μin the Milky Way

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The Distribution of Atomic Carbon in the Orion Giant Molecular Cloud 1

Cited by 118 publications

References 46 publications

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci3PP0observations

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci3PP0observations

Weak13CO in the Cloverleaf quasar: evidence for a young, early generation starburst

Searching for spatial variations ofα2/μin the Milky Way

Contact Info

Product

Resources

About

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Physical conditions of molecular gas in the Circinus galaxy Multi-JCO and Ci³PP₀observations

Weak¹³CO in the Cloverleaf quasar: evidence for a young, early generation starburst

Searching for spatial variations ofα²/μin the Milky Way